The present invention relates to a torque intensifying tool.
In tightening fasteners, once the nut hits the flange surface the turning degree to tighten it up is very little. What the customer wants, on the other hand, is high turning speed so that a nut can be run down or off very fast.
The usual impact wrenches, which provide a high run down and run off speed, have the disadvantage that they are not very accurate and very slow once the nut hits the flange face. Torque power tools are torque accurate, but relatively slow in run up and run down of fasteners. Yet, still they are faster than impact guns once the nut is turned on the flange face. Torque power tools usually have an air, electric or hydraulic motor. It turns gears, which reduce the speed but increases the relatively low torque output of the motor. The higher the torque, the larger the gear ratio and obviously the slower the speed with which the nut is turned. It is, therefore, common to have a two speed mechanisms; one for run down and run off and one for the final higher torque.
It is known that running a nut down takes usually less torque than running it off due to possible thread corrosion when loosening a nut. This means that the torque derived by means of an air motor used for smaller air wrenches might have to be increased with a small intensifier to increase the turning torque provided by the motor without lowering the run up and run off speed too much. For most hand held torque power tools where the motor housing is independent to the gear housing it becomes important that the free motor-turning torque does not exceed the hand torque resistance or the tool's motor housing can not be held and starts spinning in the hand.
There are many motor driven torque multipliers in the market and some of them have two speed mechanisms, some of them react on the bolt tip, others with a reaction arm. What they all have in common is that no matter what torque or speed is applied by them their gear housing turns in the opposite direction to the output shaft. None provides a run down or run off speed where the entire gear housing together with the inner gear assembly and the output drive turn at the same high speed in the same direction.
There are also portable power driven tools in the market such as disclosed in U.S. Pat. No. 2,569,244 where a push of the tool onto the fastener increases or decreases the air inlet and thus the torque output. There is, however, none in the market where a push onto the fastener changes from turning the gear housing, its gears and its output shaft in the same direction at the same speed to applying a turning force to the gears and the output shaft in one direction and simultaneously an opposite turning force to the gear housing. There are also portable power driven tools in the market where the torque of the motor can be reduced to increase the motor speed and thus the speed of the tool.
Also, the two speed mechanism of motor driven torque multipliers usually works in a way that one or several planet gear stages are disconnected so that merely the remaining ones function. This reduces the gear ratio to obtain a higher speed and lower torque and so that once the nut stalls out all planet gear stages become functional to achieve the higher torque at a lower speed. Nevertheless, the housing still wants to react in the opposite direction to the turning direction of the gears in low ratio and high ratio. In other words, while the drive and the gears receive a turning force in one direction, the housing receives the same turning force in the opposite direction. The problem with that is that a high speed, the gears and the output shaft turn so fast in the gear housing that almost all turning parts require bearings, which makes the tool larger and heavier.